What is at the center of our solar system? Why do we call it a solar system? The sun

Solar System- why do we call it a system? The word "solar" is taken from the Latin word for sun, Sol, leading to the term solar system, or the system of the sun.

- to spin on an axis. Gives us day and night. Rotate

Rotate- to spin on an axis. Gives us day and night.

- planets orbiting around the sun. Revolution

Revolutions- Gives us our seasons, along with the tilt of Earth on its axis.

Revolution Seasons

What two factors keep planets orbiting around a star like the sun? Inertia An object in motion will remain in motion. An object at rest will remain at rest. UNTIL… Force that holds planets in orbit around the sun. Gravity

Gravity and inertia are the two factors that keep planets orbiting around a star like the sun.

An object with greater gravity can capture an object with lesser gravity in orbit around it.

The larger the mass the greater the gravitational pull.

Why aren’t we pulled into the sun? Inertia An object in motion will remain in motion. An object at rest will remain at rest. UNTIL…

Let’s consider how changing inertia and/or gravity would affect the position of a planet in space…

What would happen if the gravity of the sun, for example, increased?

What would happen in the gravity of the sun, for example, decreased?

What would happen in the inertia of the Earth, for example, increased (sped up)?

What would happen if the inertia of the Earth, for example, decreased (slowed down)?

So how big is the sun?

Solar flare About 1 million Earths could fit inside the sun

The Sun

Why are there stars (such as the sun)? They are the result of constant nuclear fusion: Helium (He) Heat energy Light energy H + H Hydrogen

Where does this nuclear fusion occur in a star (such as our Sun)? He Heat energy Light energy H + H In the core…

What is the core of any star (such as the Sun)? It’s the innermost part of the star where fusion occurs. When the energy source of the Sun, its H, is “used up,” the Sun will no longer give off heat or light energy. It will “die.”

How old is our sun? Our sun is about 5 billion years old. It is believed that the sun will last about another 5 billion years.

Sun exterior is 10,000 o F Interior is 29 million degrees F Distance is 93 million miles from Earth

The core is the ‘part’ of the sun in which fusion occurs, so it’s like the “birthplace” of the star… What is the rest of the sun made of? Layers of atmosphere CORE ATMOSPHERE

The sun’s visible layer, the Photosphere, is the layer of gas that we ‘see.’ WARNING: Do NOT look directly at the sun, especially not through a camera or telescope! Source:

This photo clearly shows the red Chromo- sphere, which is the layer above the photo- sphere. Source:

This photo of the chromosphere was taken with a special camera, so you can clearly see that it is a red layer that completely surrounds the sun. In this photo, you can also see the brighter photosphere ‘peeking through.’ Image Credit: Courtesy of SOHO/EIT consortium. SOHO is a project of international cooperation between ESA and NASA

You can see the very faint, usually invisible outer layer of gas called the corona. Do you see what appears to be a halo or crown?

What are some of the features of the sun? v Prominence Sunspots v Solar Flare

SUNSPOTS

What do sunspots really look like (close-up view)? v v Credit: Swedish Royal Academy of Sciences. See:

What are sunspots? v Sunspots v Are they darker or lighter than the rest of the Sun? Do you think that they are areas that are cooler or warmer than the rest of the Sun?

P rominence - arching of gases on the sun

Here’s a great close-up photograph of a prominence… H-alpha image from Big Bear Solar Observatory

Solar flare- sudden temporary outburst of energy from a small area of the sun's surface.

What Kinds of Energy are Emitted by the Sun?

What kind of energy that is emitted by the sun is depicted here? Electromagnetic Energy in the form of visible light Because of this form of energy from the sun, humans can see! It’s hard to see in darkness!

What kind of energy that is emitted by the sun is shown here? Thermal Energy (Heat) v v Thermal energy (another kind of radiant energy or radiation) warms our planet, so we don’t freeze!

What kind of energy that is emitted by the sun is depicted here? v v Electromagnetic and Radiant (radiation) Energy in the form of Ultraviolet Light (UV), which can cause damage to human tissue (including skin and eyes)

Solar eclipse- moon blocks out most of sun and we are able to see the corona.